The present invention relates to coupling structures to permit concrete slabs to be lifted, tilted, hoisted or otherwise handled by means of suitable equipment such as cranes.
Coupling structures of the type to which the invention refers are known in general. Usually they are comprised of an anchor part which is embedded in the concrete and forms a socket opening. This anchor part cooperates with a release type coupling element which can be connected to the anchor part and released therefrom. The hoisting, lifting or other equipment is connected or connectible to that release type coupling element so that this equipment can move the concrete slab when the coupling is made up, but slab and equipment can be separated upon release of the coupling.
A typical example of this type of coupling is disclosed for example in U.S. Pat. No. 4,017,115. Simplified versions are contained in U.S. Pat. No. 3,680,906 and 3,652,118, which do not, however, show quick release type constructions. The principle of a quick release type coupling is, of course, quite old and known in numerous versions. Common to these is that a displacement element is placed behind a shoulder or the like to complete the coupling. However, it is not believed that release type couplings for use with concrete parts and requiring, therefore, very sturdy construction, are known at the required degree of simplicity deemed essential for handling.